Ian Douglas ScottandVictoria Brekenfeld
22e5cf3801
I have included information about various things I've used for debugging COSMIC. More could definitely be added. It seems good to have some central resource for this. Though not everything listed here is very straightforward to use.
2.3 KiB
Debugging COSMIC
An assortment of useful tools and settings for debugging COSMIC.
Logs
Cosmic-comp, cosmic-panel, and other components log to stderr, as well as journald (if present).
Wayland and X11 Protocols
Run clients with WAYLAND_DEBUG=1 to see what wayland calls are made. xtrace -n <command> can be used to see what X calls an X11 client is making.
XWayland
A tool like xprop can be used to determine if an application is running in XWayland. If xprop is unable to select a window, it is a native Wayland window.
Performance
sudo perf top can be used to see what functions, across all processes, are using the most CPU time. The -p argument can be used to restrict this to a single process. The output is more useful for executables with debug symbols.
cosmic-comp integrates Tracy for profiling. It can be built with cargo build --features profile-with-tracy --profile fastdebug, then the Tracy client can connect from the same system or a different one
Graphics drivers
eglinfo and vulkaninfo indicate what graphics cards and drivers are in use for hardware-accelerated rendering.
On systems with NVIDIA graphics, nvidia-smi has information about the GPU and driver.
DRM
The Linux DRM subsystem handles graphics cards and display controllers.
drm_info prints information about the outputs, planes, etc. associated with each GPU and their properties. The output of this command can be useful for understanding display related issues.
https://gitlab.freedesktop.org/wlroots/wlroots/-/wikis/DRM-Debugging documents how to configure DRM to enable additional logging, which can be useful for understanding some DRM driver issues.
Frozen desktop
If the desktop is frozen and ctrl+alt+f* don't work to change to a TTY, the magic SysRq key with r can be used to swich input in raw mode, so the kernel will handle the tty switch key binding. /etc/sysctl.confor/etc/sysctl.dmay need to be edited first to setkernel.sysrq=1` or another value that allows this command.
It is also possible to connect over ssh from another computer.
Then pidof cosmic-comp can be used to get the PID of the compositor. Then it is possible to investigate further with tools like gdb, using sudo gdb then attach <pid>.